package com.hlkj.util.dom4j;

import java.util.HashMap;

@SuppressWarnings("unchecked")
public class MyHashMap<K, V> extends HashMap {
	public static final long serialVersionUID = 1L;

	@Override
	public Object put(Object key, Object value) {
		// 如果已经存在key，不覆盖原有key对应的value ,仍然显示先前key对应的value
		if (!this.containsKey(key))
			return super.put(key, value);

		return null;
	}
}